Italian police say 21 people have been detained on suspicion of transporting new Syrian migrants into Germany, Austria and France in a fleet of old cars.

Police say 10 of the 18 drivers arrested in Germany and Austria were Italian, but that the main organizers of the land-based smuggling network that charged 500 euros per passenger were Syrian, Egyptian and Tunisian.

They said in a statement Tuesday that the taxi network ferried 200 migrants north from Italy and Hungary from December 2014 to May 2016.

Police say the Como, Italy-based organizers recruited the drivers and provided them with 170 different used cars, many owned by fictitious companies.

The investigation began in September 2015 when an Italian was arrested in Hungary with several undocumented migrants in his car, according to Eurojust.